Project Summary/Abstract Primary breast cancers systemically disseminate at very early stages of disease, often times even before the primary tumor is diagnosed. Therefore, patients that have surgery to remove primary tumors already harbor disseminated disease. Outgrowth of these disseminated micrometastases can be triggered years to decades after the primary lesion is removed, leading to inhibition of vital organ function and patient lethality. Currently, environmental stimuli that are responsible for triggering metastatic outgrowth are not well defined. In particular, population studies investigating alcohol consumption and breast cancer recurrence have yielded controversial results. A confounding factor for this disparage may be inaccurate reporting about the amount and duration of alcohol consumption. Therefore, the major OBJECTIVE of this proposal is to evaluate the ability of moderate, binge, and excessive alcohol consumption to break systemic breast cancer dormancy leading to progression of metastatic disease. To accomplish this objective, we will utilize controlled rodent models of differential alcohol intake together with an in vivo bioluminescent reporter system of epithelial-mesenchymal transition (EMT). EMT is strongly linked to breast cancer progression, including development of stem-like tumor cells that have an increased capacity to initiate metastatic tumors. Furthermore, previous in vitro studies suggest that alcohol stimulation can induce an EMT-associated transcriptional program. Therefore, in AIM1 of our proposal mice bearing systemically dormant EMT reporter tumor cells within the lungs and liver will be treated with our established moderate, excessive and binge alcohol consumption protocols. Our bioluminescent approach will allow us to longitudinally track these cohorts of control and alcohol drinking mice for induction of EMT in tumor cells harbored within these common organ sites of breast cancer metastasis. In addition to directly acting on tumor cells, alcohol can profoundly alter the fibrotic and immune makeup of metastatic organ sites. Maintenance of tissue compliance and immune surveillance are two critical mechanisms by which the lungs and liver resist metastatic colonization. In AIM2 of our proposal, postsurgical animals bearing matrix-sensitive and immune-sensitive dormant tumor cells will be treated with our differential alcohol consumption protocols. These animals will be evaluated for an impaired ability to maintain tumor cell dormancy within these critical vital organs. Results gained by our collaborative studies will result in new insight into the mechanisms by which alcohol may contribute the metastatic recurrence of breast and potentially other cancers. !